A quick and easy performance improvement

denis at croombs.org denis at croombs.org
Wed Jul 26 15:56:46 IST 2006

> I thought I'd post to the list about a change I made yesterday which
> provided a huge boost in system's performance.
> By far the largest amount of time spent in the life of a disk I/O
> operation is seek time.  Seek time is the amount of time it takes to
> move the disk R/W heads from one cylinder to another.  The /var/spool
> filesystem is where the inbound and outbound mail queues are located.
> Note also that the Bayes database is accessed heavily when analyzing a
> message.
> Like many installations we have our root filesystem (/) and /var
> filesystem on separate partitions on a single hard drive.  The default
> location for the SpamAssassin bayes database is in /root/.spamassassin/
> which is on the rootfs.   Moving the bayes database to
> /var/spool/spamassassin resulted in a huge decrease in IOWait time.  In
> our case it was an order of magnitude reduction.  For example,  IOWait
> percentages went from 30% to 3%.  IOWait is the percentage of time the
> processor is waiting on an I/O operation to complete.  Our mail queues
> no longer get behind and throughput is outstanding!
I would also assume having them on different hard drives would give an
even larger increase in throughput ?



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